Thought I would share this information as I just got my truck back from the mechanic, for anyone who might experience a similar problem. I have a 1998 Quad Cab 4x4, 360. Transmission went out at 60,000 miles and the dealer "rebuilt" it. Within a year, I started hearing a noise in the drivetrain. At first it was a low rumbling noise that was only audible when slowing down below 25 mph. Took it to a mechanic, couldn't tell what it was. The noise got worse and eventually you could hear itwhether slowing down or speeding up. Another mechanic couldn't tell what it was. The noise got worse and you could hear it whenever driving at any speed. A third mechanic said it was the transfer case and you could replace it or wait until it goes out and then replace it. He said it won't hurt anything but the noise will keep getting worse until it does go out. Drove it for another year, with the noise getting progressively worse until just a few weeks ago, it finally sounded like the truck was falling apart. On the way home that night, it also felt like the transmission was slipping a little. Parked the truck and called a new mechanic suggested by a co-worker. He said to bring it in. On the way there, the OD locked out and the transmission temp light came on. Not a good sign!

Well, he checked it out and confirmed that yes, the transmission had failed again (90,000 miles on the rebuilt transmission). He ordered a certified rebuilt transmission and while waiting for it, took apart the transfer case to see if he could rebuild it without replacing the whole thing. There was absolutely nothing wrong with the transfer case! He determined that the rear bearing on the transmission had failed that was causing the noise to come from the transfer case. The rebuilt transmission was installed and there is absolutely no noise. The rebuilt transmission also came with a new radiator because of the tendency for a failed transmission to introduce metal particles into the cooler AND a new auxiliary transmission cooler. Needless to say, I will never do anything with that dealer again (although I made that decision before this happened). So, for those of you hearing this noise, it might also be your transmission (in addition to your axle bearings or transfer case).

 

Your problem probably started with a restricted trans cooler. Lots of shops don't flow check the cooler when repairing or overhauling automatics. All dodge dealers should have the tools to do it. I'm pretty sure its considered essential equipment. I myself have been caught by not checking it before reassembling. Spent all afternoon overhauling the trans, didn't check the cooler. One trip around the block and out comes the tranny again for repair. checked the cooler 85% plugged. replace cooler and overhauled trans AGAIN (for free) and all is well.

My own damn fault for being in a hurry.
The rear bearing failing in the overdrive section is a classic sign or a restricted cooler. It has to get its lube from the return line from the trans cooler. I've seen a few overdrives that got so hot the gears turned black.

Always flush or check the trans cooler!

 

how do you flush it ? can you backflush with air pressure ?

 

The proper way is with mineral spirits and a special pump with a pressure gauge. It would be tough to make your own. I've seen a few aerosol kits that would flush but not check flow. You certainly can blow some air through it if nothing else. There is a strong check valve in the trans pressure line that can skew diagnosis so if your going to attempt something so disconnect at the trans cooler if your going to flush or reverse flush.